1. FIELD OF THE INVENTION
The present invention relates to a voltage regulating system for voltage regulators installed in automotive vehicles, and more particularly relates to a system which is capable of regulating output voltage of a battery charging generator even when the generator and a battery becomes disconnected and when the normal voltage sensing circuit of the voltage regulator becomes disconnected from the generator and the battery, and further capable of indicating the disconnection in the system.
2. DESCRIPTION OF THE PRIOR ART
A conventional well-known voltage regulator of this kind is provided with an output transistor for controlling field current flowing through a field winding of a battery charging generator, a voltage sensing circuit for sensing the voltage of the battery and a transistor circuit including a control transistor effected by the voltage sensing circuit and controlling the output transistor. The field winding is supplied with current by three auxiliary diodes connected to the battery charging generator. The voltage sensing circuit is connected across the battery, which is connected to a power bridge rectifier of the generator by means of a power supply cable.
However in this conventional voltage regulator, if the positive terminal of the power bridge rectifier or the voltage sensing circuit becomes disconnected, the output transistor of the voltage regulator is continuously biased conductive to thereby result in uncontrolled high voltage which would destroy electrical components of the system. And another disadvantage resides in that this conventional system has no means to inform a driver of the disconnection causing uncontrolled high voltage.